07/18/2026
This does not apply to our area of Florida currently but the northern states are undergoing an onslaught of wildfire related smoke and based on all the questions we are answering in Horse Vet Corner and the posts Iโm getting in my feed, Iโd like to educate on an important topic.
Nebulization therapy.
Scrolling through my feed and I see a post advertising someone going around to barns offering to nebulize colloidal silver to those affected by wildfire smoke/high AQI.
There is currently NO peer-reviewed in vivo evidence demonstrating that nebulizing colloidal silver (or silver nanoparticles) improves respiratory disease in horses. There is one frequently cited study, but it is important to understand what it actually showed.
What evidence does exist?
The primary equine study is:
Frippiat et al., Journal of Equine Veterinary Science (2021)
This study evaluated nebulized silver nanoparticles against two common equine respiratory pathogens:
* Streptococcus equi subsp. zooepidemicus
* Actinobacillus equuli
The key findings were:
* Silver nanoparticles inhibited bacterial growth in vitro (in broth culture and on agar plates).
* Nebulization did not destroy the antimicrobial activity of the silver nanoparticles.
* The authors concluded that silver nanoparticles *might* represent a future treatment option *IF* safety and efficacy could be demonstrated in live horses.
What the study did NOT show
It did NOT demonstrate:
* improved clinical signs
* faster recovery
* reduced bacterial burden in the lungs of horses
* improved airway inflammation
* improved performance
* safety after repeated inhalation
In other words, it was a laboratory microbiology studyโnot a clinical trial.
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Colloidal silver vs. silver nanoparticles
This distinction matters.
Commercial โcolloidal silverโ products are highly variable:
* particle size
* ionic silver concentration
* stabilizers
* purity
The published study used a defined silver nanoparticle preparation, not the typical over-the-counter colloidal silver products marketed online. Therefore, the study cannot be generalized to commercial colloidal silver preparations.
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What about safety?
Silver has recognized antimicrobial activity, but inhalation raises several unanswered questions:
* deposition within distal airways
* clearance by mucociliary transport
* uptake by alveolar macrophages
* oxidative stress
* chronic inflammatory responses
* accumulation in pulmonary tissue
Human toxicology literature on inhaled silver nanoparticles suggests that sufficiently high exposures can induce pulmonary inflammation and oxidative injury, although the relevance to therapeutic equine dosing is unknown. Importantly, this has not been adequately studied in horses.
The equine authors themselves emphasized that toxicity studies are needed before clinical use.
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Any evidence for equine asthma (RAO/SEA/IAD)?
None that Iโm aware of.
There are no peer-reviewed clinical trials showing benefit for:
* Severe Equine Asthma (SEA/RAO)
* Mild-Moderate Equine Asthma (formerly IAD)
* EIPH
* viral respiratory disease
* inflammatory airway disease
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If the target is bacterial pneumonia
Nebulization itself is well established as a drug delivery method, but the agents with evidence include:
* sterile saline
* hypertonic saline (selected cases)
* nebulized antimicrobials in very specific situations
* mucolytics (with mixed evidence)
* bronchodilators
* inhaled corticosteroids for asthma
Silver is not part of any evidence-based equine respiratory treatment guidelines.
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Overall assessment
The concept is scientifically plausible enough to justify further RESEARCH, but the leap from โkills bacteria in a petri dishโ to โhelps horses breathe better without causing harmโ has not yet been made. At present, there is no peer-reviewed clinical evidence supporting routine nebulization of colloidal silver in horses, and there are unresolved safety concerns regarding inhalation.
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In addition to ALL of that, do you really want someone to come to your barn whose tools were on the nose of another unknown horse? I know theyโll come at me saying they clean their equipment - but how well can you clean if youโre running from barn to barn doing this.
Inhalation of essential oils can also be dangerous and should not be done.
If you are convinced that nebulizer therapy is needed and you cannot get a hold of your veterinarian, ensure that the person who is doing the nebulization therapy sterilizes the nebulizer tubing and mask between each patient. Risk of transmitting respiratory disesases such as strangles, EHV-1/4, influenza, etc are real and possible. With at least strangles, there are asymptomatic carriers โ just like COVID.
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Save your money. If ANYTHING, nebulize saline.
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More reading:
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The severe fires throughout California over the past three months have exposed humans and animals to unhealthy air containing wildfire smoke and particulates. These particulates can build up in the respiratory system, causing a number of health problems including burning eyes, runny noses and illnes...
